Hydraulic fracturing to stimulate a subterranean formation includes injecting a fracturing fluid through a wellbore into the formation at a pressure and flow rate at least sufficient to overcome the pressure of the reservoir and extend fractures into the formation. A high pressure line directs the fracturing fluid through a wellhead and into the wellbore. The fracturing fluid is a mixture of a liquid and a media, and is typically injected into the wellbore at high pressures, in the range of about 10,000 to 30,000 psi.
To protect the integrity of the wellhead and to reduce equipment failures, such as blown tubing or pumps, a relief valve associated with the high pressure line in the system maintains pressure at or below a rated limit for the associated fracturing equipment. However, the relief valve has traditionally been difficult to calibrate in the field and is subject to wear as pressure fluctuations occur, resulting in valve chatter, increased wear, and ultimately a less than accurate popoff pressure limit on the relief valve. Therefore, what is needed is an apparatus or method that addresses one or more of the foregoing issues, among others.